CVE-2018-21141 in R6100
Summary
by MITRE
Certain NETGEAR devices are affected by denial of service. This affects R6100 before 1.0.1.22, R7500 before 1.0.0.122, R7800 before 1.0.2.42, R8900 before 1.0.3.10, R9000 before 1.0.3.10, WNDR3700v4 before 1.0.2.96, WNDR4300 before 1.0.2.98, WNDR4300v2 before 1.0.0.54, WNDR4500v3 before 1.0.0.54, and WNR2000v5 before 1.0.0.64.
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Analysis
by VulDB Data Team • 06/01/2024
The vulnerability identified as CVE-2018-21141 represents a denial of service condition affecting multiple NETGEAR router models within their consumer and small office networking product lines. This issue specifically targets firmware versions of several popular NETGEAR routers including the R6100, R7500, R7800, R8900, R9000, WNDR3700v4, WNDR4300, WNDR4300v2, WNDR4500v3, and WNR2000v5 models. The affected devices are susceptible to a condition that can cause them to become unresponsive or cease normal network operations, effectively disrupting network connectivity for users within their coverage areas. This vulnerability falls under the category of CWE-400, which encompasses improper handling of resources that can lead to denial of service conditions, making it particularly concerning for network infrastructure devices that are expected to maintain continuous availability.
The technical flaw manifests through insufficient input validation and error handling within the affected router firmware implementations. When specific network traffic or administrative commands are processed by the vulnerable devices, the firmware fails to properly validate or sanitize incoming data, leading to a state where the device's processing capabilities become overwhelmed or corrupted. This typically occurs when malformed packets or unexpected command sequences are received through the device's network interfaces or management portals. The vulnerability operates at the application layer of the network stack and can be triggered through various means including direct network communication or through management interfaces that are accessible to authorized users. The underlying issue demonstrates poor defensive programming practices where the firmware does not adequately protect against malformed inputs that could cause the device to crash or enter an unrecoverable state.
The operational impact of this vulnerability extends beyond simple network disruption to potentially affect business continuity and user productivity in environments where these routers serve as primary network infrastructure. Organizations relying on affected NETGEAR devices may experience unexpected network outages, particularly during peak usage periods when the devices are processing multiple concurrent connections. The vulnerability affects devices that are commonly deployed in both residential and small business environments, making the potential impact widespread and varied. Network administrators may find their devices becoming unresponsive during routine maintenance operations or when under normal operational loads, forcing them to perform manual device resets or even physical reboots to restore service. The attack surface is particularly concerning because these devices are often deployed in environments where physical access is limited, making remote recovery operations challenging and potentially requiring on-site technician visits.
Mitigation strategies for CVE-2018-21141 primarily involve firmware updates provided by NETGEAR to address the underlying validation and error handling flaws within the affected device implementations. Users should immediately check for and install available firmware updates for their specific device models to remediate this vulnerability. Network administrators should implement monitoring solutions to detect unusual network behavior or device unresponsiveness that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1499.004 which involves network denial of service attacks, and represents a common pattern of insufficient input validation that can lead to system instability. Organizations should also consider implementing network segmentation strategies to limit the impact of device failures and establish redundant network paths to maintain service availability. Regular firmware update policies should be established to ensure all network infrastructure devices remain protected against known vulnerabilities. The incident highlights the importance of maintaining up-to-date firmware for network devices and demonstrates how seemingly minor implementation flaws can have significant operational impacts on network reliability and availability.